This invention relates to tufting machines and more particularly to a yarn feed system having a fault detector for stopping the tufting machine when the feeding of the yarn does not conform to that called for by a pattern controller.
In tufting machines, a plurality of yarn carrying needles are mounted on one or more needle bars extending transversely across the machine and reciprocated cyclically to penetrate and insert loops of yarn into a backing material moving longitudinally beneath the needles. The loops thus formed are seized either by loopers or hooks mounted on a hook bar and either shed or held and thereafter cut depending upon whether it is desired to produce loop or cut pile in the material. When a substantial amount of versatility in patterning in the tufted fabric is desired, it is known to provide each needle with a sew/no-sew capability by mounting the needles on individual needle carriers which are reciprocated selectively in accordance with a pattern by either being latched to or disengaged from a reciprocating latch bar, the latch bar being reciprocably driven continuously from mechanism driven by a rotating main shaft mounted in the head of the tufting machine. When latched to the latch bar, the needle carrier and the respective needle or needles reciprocate into cooperation with the hook or looper to form a loop which is thereafter cut. The latching occurs by means of latch pins on pneumatic cylinders driven in accordance with a pattern. Machines of this type are known as controlled needle machines, and when each needle is individually controlled in this manner, it is known as an individual controlled needle machine. Examples of such machines are illustrated in U.S. Pat. Nos. 3,115,856; 3,259,088; 3,881,432 and 3,986,465.
A problem encountered in relation to machines of this type may occur if the feed of yarn to one or more needles is not correct, for example, either the yarn required is not being fed to a particular needle or if a yarn is being fed when one is not called for due to a failure in the yarn feed system. If, there is a yarn breakage, unthreading of the yarn from a needle or exhaustion of the supply of yarn from which the yarn is fed, it may not normally be possible to detect such fault conditions to prevent errors in forming the tufted fabric. In some cases a yarn may be picked up by an adjacent needle, and in the case of an individually controlled needle machine if a needle is latched, a yarn end that has been,cut may extend into the backing which may grab and pull the yarn past the yarn clamp from the creel. Thus, a reduction in quality of the finished tufted fabric or the production of commercially useless finished fabric may occur in these cases.
The known fault detection devices sense whether any yarn being fed to the eye of any needle has either broken or unthreaded, i.e., whether yarn if being fed. Since these devices have been associated solely with tufting machines wherein all yarns are to be fed continuously to every needle, they have no applications to a controlled needle machine as described above since they would provide a false reading when a needle which is not being fed with yarn is not supposed to be fed with yarn. Examples of the known yarn break detectors/stop motion devices of this type include U.S. Pat. Nos. 3,529,560; 3,764,773; 5,687,095; 4,522,139 and 5,005,503.